Synthesis of Fe₃O₄@Zeolite NaA from rice husk ash for efficient methylene blue adsorption

This study synthesized Fe3O4@zeolite NaA with SiO2 from rice husk ash and evaluated its adsorption of methylene blue from water. As-synthesized adsorbent was characterized by advanced analytical methods. The results showed that the adsorbent was in the size of 0.981±0.235 μm with a cubic and spherical shape and its specific surface area, pore diameter, and pore volume of 82.41 m2/g, 1.019 nm, and 0.224 cm3/g, respectively. The Fe3O4@zeolite NaA magnetization was 17.65 emu/g, and its point of zero charge was at 7.48. The adsorption achieved the highest efficiency of 86.5% at room temperature, pH 9 within 25 min with an initial concentration of 20 mg/L. This adsorption was a physical interaction and fitted to pseudo-second-order kinetics and Freundlich isotherm. Fe3O4@zeolite NaA was magnetically separated from the solution using a magnet and could be reused for two to three cycles. These findings suggested that Fe3O4@zeolite NaA can be a potential adsorbent for dye removal in industry.